AU2023100088B4

AU2023100088B4 - Seismic restraint of ceilings

Info

Publication number: AU2023100088B4
Application number: AU2023100088A
Authority: AU
Inventors: Sasan SAIDIAN
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-01-25
Filing date: 2023-10-11
Publication date: 2024-06-06
Anticipated expiration: 2029-06-08
Also published as: WO2022155698A1; AU2021103213A4; US20230417055A1; AU2023100088A4; AU2021103213B4; AU2021421274B2

Abstract

Abtract A seismic restraint system for suspended ceilings has longitudinal ceiling perimeter restraint members each having a longitudinal web, a longitudinal bottom flange extending orthogonally from the web, integrally formed fixed connection apertures and floating connection slots orthogonally orientated with respect to the web. In use a pair of ceiling perimeter restraint members are installed horizontally at opposite sides of a suspended ceiling which has a grid of intersecting structural rails. Each ceiling perimeter restraint member is installed with the web attached to a respective adjacent structure with the bottom flange thereof extending away therefrom and with respective ends of the structural rails resting thereatop. Each structural rail running longitudinally between the ceiling perimeter restraint members is fixed in place at one end using at least one of the fixed connection apertures and slidably affixed at an opposite end using at least one of the floating connection slots. 16

Description

Abtract

A seismic restraint system for suspended ceilings has longitudinal ceiling perimeter

restraint members each having a longitudinal web, a longitudinal bottom flange

extending orthogonally from the web, integrally formed fixed connection apertures

and floating connection slots orthogonally orientated with respect to the web. In use a

pair of ceiling perimeter restraint members are installed horizontally at opposite sides

of a suspended ceiling which has a grid of intersecting structural rails. Each ceiling

perimeter restraint member is installed with the web attached to a respective adjacent

structure with the bottom flange thereof extending away therefrom and with

respective ends of the structural rails resting thereatop. Each structural rail running

longitudinally between the ceiling perimeter restraint members is fixed in place at one

end using at least one of the fixed connection apertures and slidably affixed at an

opposite end using at least one of the floating connection slots.

Seismic restraint of ceilings

Field of the Invention

[0001]This invention relates generally to arrangements for restraining building elements from perimeter supporting structures. More particularly, this invention relates to methods and components for seismically restraining suspended ceilings from perimeter walls, bulkheads or the like.

Background of the Invention

[0002] Ceilings are typically made from a suspended metal grid of intersecting structural rails, wherein ceiling panels or tiles are laid in or fastened to the grid.

[0003] The ceiling grid may run on a single plane with mechanically interlocking rails (e.g. interlocking T-rails) or may be installed on two different levels with a mechanical device connecting the intersecting rails, such as wherein lower furring channels are connected to orthogonal top cross rails with locking keys.

[0004] These ceilings may be seismically restrained by connecting their perimeter to an abutting structure, such as a wall or bulkhead. According to this method, horizontal seismic actions within the ceiling system are transferred to the perimeter structure.

[0005] 'Perimeter restraint' requires that every primary and secondary grid member shall have one end fixed (to provide seismic restraint) and the other end floating (to provide seismic isolation) at the perimeter.

[0006] As is shown in Figures 1 and 2, normal practice is for the ceiling to be fixed on two adjacent sides and floating on the opposing two adjacent sides.

[0007] For flush-grid ceilings (e.g. ceilings comprising intersecting T-rails), the seismic load path along the grid members is provided by the mechanically interlocking rail connections. Current industry practice involves the use of proprietary perimeter seismic clips 129 as is illustrated in Figure 3, that allow for either a fixed or floating connection at either end of each grid member.

[0008] At the fixed end 121, seismic loads within the ceiling system are transferred to the perimeter supporting structure via the axial stiffness of grid members. At the floating end 120, the ceiling system is seismically isolated from the perimeter structure to avoid unwanted load swaps, as required. Seismic clips prevent the spreading of grid ends and provide stability at ceiling perimeters. Also, seismic clips prevent grid ends from sliding off at the edges. These clips are connected discretely at each terminal end of each grid member. When connecting to a cavity wall (e.g. dry wall), an additional nogging member 130 is required to be installed within the wall cavity, to provide fixing support for the perimeter clips. This imposes additional labour and material cost and effort.

[0009] For the case of ceiling grids having over-crossing rails (e.g. ceilings comprising

lower furring channel and orthogonal top cross rail-type grids), the intersections 131

between the upper and lower grid members must be restrained by additional means,

as conventional devices such as locking keys are typically designed to provide gravity

support only, not lateral restraint.

[0010] Failing to restrain grid intersections may result in sliding between intersecting

grid members under horizontal loads, which defeats the purpose of seismic restraint,

or may result in disengagement of the lower furring channel from the top cross rail

and subsequent progressive collapse of the entire ceiling, a phenomenon commonly

known as 'blanket collapse' which compromises life safety and may result in

catastrophic fatalities. Provision for such intersection restraint incurs additional

labour and material cost and effort.

[0011] It is to be understood that, if any prior art information is referred to herein, such

reference does not constitute an admission that the information forms part of the

common general knowledge in the art, in Australia or any other country.

Summary of the Disclosure

[0012] There is provided herein embodiments of a seismic perimeter restraint system

for suspended ceilings comprising top cross rails and furring channels wherein the

furring channels are fixed to a longitudinal ceiling perimeter restraint member and

slidably retained by respective slots orientated along their lengths to an opposite

longitudinal ceiling perimeter restraint member, thereby forming what is referred to

herein as a laterally-restrained floating connection. Furthermore, ends of the top

cross rails are not fixed with respect to an adjacent structure.

[0013] In effect, the ceiling is restrained in both orthogonal directions only by the lower

furring channels, whilst maintaining floating sides, as required. Seismic loads within

the ceiling system are transferred to the perimeter structure via the axial, flexural and

shear stiffnesses of the furring channels.

[0014] As such, the present system provides restraint in both orthogonal directions

only by the lower furring channels, without relying on the top cross rails, saving time

and money. This arrangement may also reduce or eliminate the requirement for

additional horizontal restraint at ceiling grid intersections.

[0015]This arrangement is particularly suitable for restraining ceilings in long

corridors, which is generally challenging to achieve by conventional perimeter

restraint methods, as the length at which the ceiling can be restrained is limited by

the connection capacity at the adjoining wall at the corridor end, whereas according

to the present method, a finite seismic mass is attributed to a single furring channel

which can be repeated along the length of the corridor, virtually without limitation.

[0016] The ends of the top cross rails are preferably spaced away from the adjacent

structures.

[0017] The opposite longitudinal ceiling perimeter restraint member preferably has a

web and a horizontally projecting flange having the slots slidably engaging respective

furring channels.

[0018] Both restraint members preferably have apertures and the slots for

interchangeable use on either side of the furring channels to form a fixed connection

or a sliding connection respectively.

[0019]There is also provided a method of seismically restraining a suspended

ceilings comprising top cross rails and furring channels by horizontally restraining the

ceiling in both orthogonal directions only by the lower furring channels, without

forming fixed connections with the top cross rails to an adjacent structure.

[0020] Other ceiling types may be restrained similarly and other seismic ceiling

restraint aspects are also disclosed.

Brief Description of the Drawings

[0021] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0022] Figure 1 shows a plan view of a seismically restrained ceiling in accordance with the prior art;

[0023] Figure 2 shows a cross-sectional elevation view of the seismically restrained ceiling of Figure 1;

[0024] Figure 3 is a perspective view of ceiling perimeter seismic restraint in accordance with the prior art;

[0025] Figure 4 shows a plan view of a seismically restrained ceiling in accordance with the prior art;

[0026] Figure 5 shows an arrangement of a top cross rail crossing over a lower furring channel and seismically restrained with proprietary connectors in accordance with the prior art;

[0027] Figure 6 shows a perspective view of a ceiling perimeter restraint member in accordance with a first embodiment;

[0028] Figure 7 shows a front elevation view of the restraint member of Figure 6;

[0029] Figure 8 shows a top plan view of the restraint member of Figure 6;

[0030] Figure 9 shows a method of restraining a ceiling with a floating connection using the restraint member of Figure 6;

[0031] Figure 10 shows an elevation view of a floating connection formed using the restraint member of Figure 6;

[0032] Figure 11 shows an elevation view of a fixed connection formed using the restraint member of Figure 6;

[0033] Figure 12 shows a T-rail-type ceiling seismically restrained using restraint members of Figure 6;

[0034] Figure 13 shows a method of seismically restraining a ceiling comprising lower furring channels and top cross rails in accordance with an embodiment;

[0035] Figure 14 shows a perspective view of a ceiling perimeter restraint member in

accordance with a second embodiment;

[0036] Figure 15 shows an end elevation view of the restraint member of Figure 14;

[0037] Figure 16 shows a top plan view of the restraint member of Figure 14;

[0038] Figure 17 shows a bottom plan view of the restraint member of Figure 14;

[0039] Figure 18 shows a perspective view of a floating connection formed using the

restraint member of Figure 14;

[0040] Figure 19 shows a perspective view of a fixed connection formed using the

restraint member of Figure 14;

[0041] Figure 20 shows a side elevation view of the floating connection of Figure 18;

[0042] Figure 21 shows a side elevation view of the fixed connection of Figure 19;

[0043] Figures 22 and 23 show top cross rail floating connections; and

[0044] Figure 24 shows a ceiling comprising furring channels and top cross rails

seismically restrained using the restraint member of Figure 14.

Description of Embodiments

[0045] A longitudinal ceiling perimeter restraint member 100 comprises a web 101

and a bottom flange 102 extending orthogonally from the web 101.

[0046]According to the preferred embodiment shown, the restraint member 100

comprises integrally formed fixed connection apertures 103 and floating connection

slots 104 orthogonally orientated with respect to the web 101. In the manner

illustrated in Figures 12 and 24, a pair of ceiling perimeter restraint members 100 are

installed horizontally at opposite sides of a suspended ceiling 105.

[0047] The suspended ceiling 105 comprises a grid of intersecting structural rails 106

which may be suspended from ceiling wires 107 attached to adjustable ceiling clips

108 thereof.

[0048] Each ceiling perimeter restraint member 100 is installed with the web 101

thereof attached to a respective adjacent structure 109, such as a wall, bulkhead or

the like, and with the bottom flange 102 thereof extending away from the structure

109. In the embodiment shown, the structure 109 is a dry-wall comprising face board

112 and vertical supportive wall studs 110 therebehind.

[0049] Each structural rail 106 running longitudinally between the ceiling perimeter

restraint members 100 rests atop respective bottom flanges 102 at either end thereof.

[0050] Furthermore, each structural rail 106 running longitudinally between the ceiling

perimeter restraint members 100 is fixed in place (i.e. a fixed perimeter connection)

at one end using at least one of the fixed connection apertures 103 and slidably

affixed (i.e. a floating perimeter connection) at an opposite end thereof using at least

one of the floating connection slots 104.

[0051]As is illustrated in Figure 9, each perimeter restraint member 100 may be

installed without additional nogging support therebehind. In this regard, for a dry-wall

application as shown in Figure 9, fasteners 111 may attach the ceiling perimeter

restraint member 100 through the face board 112 to a flange 113 of a wall stud 110

therebehind.

[0052] Each ceiling perimeter restraint member 100 may further comprise an upper

flange 114 at an opposite side of the web 101 from the bottom flange 102 and

extending orthogonally from the web 101 to the same side as a bottom flange 102.

[0053] The upper flange 114 may further comprise a lip 115 inclined away from the

bottom flange 102. The upper flange 114 and the bottom flange 102 may be spaced

apart to accommodate an end of a rail 106 therebetween whilst minimising vertical

movement. In a preferred embodiment, the upper flange 114 and the bottom flange

102 are spaced apart according to the height of the rail 106 such that an end of the

rail 106 wedges therebetween.

[0054] Furthermore, the bottom flange 102 may extend beyond the upper flange 114

and wherein the inclined lip 115 guides the top of the rail 106 in under the upper

flange 114 whilst the bottom of the rail 106 slides across the bottom flange 102

orthogonally with respect to the web 101.

[0055] Figure 12 shows an embodiment wherein the ceiling 105 comprises a flush grid

of T-rails 106. As is shown in Figure 9, each T-rail 106 may comprise a metal sheet

folded over to define a bulb 116, a web 117, and side flanges 118 extending

orthogonally from either side of the bottom of the web 117.

[0056] Figures 6 - 12 show a ceiling perimeter restraint member 100 according to a

first embodiment which is suited for T-rail-type ceilings 105. In accordance with this

embodiment, the restraint member 100 comprises a plurality of punched out tabs 119,

each being orthogonal with respect to both the web 101 and the bottom flange 102.

As is illustrated in Figure 8, an outer edge of each tab 119 may extend beyond the

bottom flange 102.

[0057] Each tab 119 may have a respective floating connection slot 104 therealong

and at least one fixed connection aperture 103 adjacent to the floating connection

slot 104. Each tab 119 may also comprise a pair of fixed connection apertures 103.

Furthermore, the pair of fixed connection apertures 103 may locate respectively

adjacent to either end of the floating connection slot 104.

[0058] Seismic ceiling restraint using the ceiling perimeter restraint member 100 of

the first embodiment is illustrated in Figures 9 - 12 wherein ceiling perimeter restraint

members 101 are affixed horizontally to adjacent structures 109 wherein, with

particular reference to the dry-wall embodiment shown, fasteners 111 along the

length of the web 101 thereof affix the web 101 directly to flanges 113 of vertical wall

studs 110 through a face board 112 thereof.

[0059] As is illustrated in Figure 10, one side of each longitudinal T-rail 106 running

between the oppositely affixed ceiling perimeter restraint members 100 may be

affixed as a floating connection 120 wherein a fastener 122 affixes the web 117 of

the T-rail 106 to a floating connection slot 104 of a tab 119. As is further illustrated in

Figure 10, the spacing between the lower flange 102 and the upper flange 114 may

be such that the T-rail 106 is wedged therebetween. In the embodiments, the spacing

between the upper flange 114 and the lower flange 102 is slightly less than the height

of the T-rail 106 such that the upper flange 114 bends upwardly slightly to

accommodate the top of the T-rail 106 thereunder when guided therein by the inclined

lip 115.

[0060] Figure 11 illustrates a fixed connection 121 at an opposite end of the same T

rail 106 wherein fasteners 122 secure the web 117 of the T-rail 106 using the fixed connection apertures 103. In the embodiment shown, a pair of fasteners 122 are used for a respective pair of fixed connection apertures 103.

[0061] Figure 12 shows the suspended ceiling 105 with the longitudinal T-rails 106

running between the oppositely affixed ceiling perimeter restraint members 100

having the floating connections 120 at one end and the fixed connections 121 at the

opposite end. The suspended ceiling 105 may be secured wherein fixed connections

121 are provided at adjacent orthogonal sides whereas floating connections 120 are

provided at opposite adjacent orthogonal sides.

[0062] Figures 13 - 24 show an embodiment wherein the suspended ceiling 105

comprises top cross rails 123 crossing over furring channels 124. Figures 14 - 17

show the ceiling perimeter restraint member 100 in accordance with a second

embodiment suited for this type of ceiling arrangement.

[0063] In accordance with this embodiment, the bottom flange 102 has integrally

formed fixed connection apertures 103 and floating connection slots 104

therethrough. In the embodiment shown, the bottom flange 102 comprises an

alternating pattern of at least one fixed connection aperture 103 and floating

connection slots 104.

[0064] The particular embodiment shown has a pair of fixed connection apertures 103

between adjacent floating connection slots 104. Furthermore, the alternating pattern

may be an equidistant pattern.

[0065] Figures 18 and 20 show a floating connection 120 wherein the ceiling perimeter

restraint member 100 is affixed to an adjacent structure 109 in the aforedescribed

manner and wherein a fastener 126 goes in underneath the bottom flange 102 through

a floating connection slot 104 and secures through a bottom web 125 of the furring

channel124.

[0066] Figures 19 and 21 show a fixed connection 121 at an opposite end of the furring

channel 124 wherein at least one fastener 126 goes through the bottom flange 102

through a respective fixed connection aperture 103 thereof and which secures

through the bottom web 125 of the furring channel 124.

[0067] As is also illustrated in Figures 18 and 19, the spacing between the upper

flange 114 and bottom flange 102 may wedge the furring channel 124 therebetween.

[0068] Figures 22 and 23 illustrate top cross rail floating connections 127 wherein the

top cross rails 123 are left floating away from the adjacent structures 109.

[0069] Furthermore, with reference to Figure 13, there is shown a way to restrain a

suspended ceiling comprising a gridwork of top cross rails 123 and lower furring

channels 124 wherein the furring channels 124 are connected with the fixed

connection 121 at one end and a laterally-restrained floating connection 128 at an

opposite end thereof and wherein the top cross rails 123 have floating connections

127 at both ends thereof. The laterally-restrained floating connection 128 is so named

because each furring channel 124 may slide relative to the restraint member 100

along the longitudinal axis of each furring channel 124 but wherein the ends of each

furring channel 124 connected to the restraint member 100 at the laterally-restrained

floating connection 128 are prevented from moving laterally with respect to the

longitudinal axis of each furring channel 124 by the respective floating connection

slot 104.

[0070] The foregoing description, for purposes of explanation, used specific

nomenclature to provide a thorough understanding of the invention. However, it will

be apparent to one skilled in the art that specific details are not required in order to

practise the invention. Thus, the foregoing descriptions of specific embodiments of

the invention are presented for purposes of illustration and description. They are not

intended to be exhaustive or to limit the invention to the precise forms disclosed as

obviously many modifications and variations are possible in view of the above

teachings. The embodiments were chosen and described in order to best explain the

principles of the invention and its practical applications, thereby enabling others

skilled in the art to best utilize the invention and various embodiments with various

modifications as are suited to the particular use contemplated. It is intended that the

following claims and their equivalents define the scope of the invention.

[0071] The term "approximately" or similar as used herein should be construed as

being within 10% of the value stated unless otherwise indicated.

Claims

Claims 1. A seismic perimeter restraint system for suspended ceilings comprising top

cross rails and furring channels wherein:

the furring channels are fixed to a longitudinal ceiling perimeter restraint

member and slidably retained by respective slots orientated along their lengths to an

opposite longitudinal ceiling perimeter restraint member; and

ends of the top cross rails are not fixed with respect to an adjacent structure.
2. The system as claimed in claim 1, wherein the ends of the top cross rails are

spaced away from the adjacent structures.
3. The system as claimed in claim 1, wherein the opposite longitudinal ceiling

perimeter restraint member has a web and a horizontally projecting flange having the

slots slidably engaging respective furring channels.
4. The system as claimed in claim 3, wherein both restraint members have

apertures and the slots for interchangeable use on either side of the furring channels

to form a fixed connection or a sliding connection respectively.
5. A method of seismically restraining a suspended ceiling comprising top cross

rails and furring channels by fixing the furring channels using a longitudinal ceiling

perimeter restraint member and slidably retaining the furring channels by respective

slots orientated along their lengths using an opposite longitudinal ceiling perimeter

restraint member, and not fixing ends of the top cross rails with respect to an

adjacent structure.